EVALUATION OF ROSGEN'S STREAMBANK EROSION POTENTIAL ASSESSMENT IN NORTHEAST OKLAHOMA1

ABSTRACT: In this study three components of the Rosgen Level III Stream Reach Condition Assessment were tested for their ability to predict short-term erosion rates. Rosgen's bank erosion potential (BEP) ratings and near bank stress (NBS) estimates and the Pfankuch channel stability ratings were evaluated. Thirty-six banks with a range of BEP ratings and NBS estimates were selected on the 101 km Upper Illinois River in northeast Oklahoma. The Upper Illinois River is a meandering, gravel-dominated, riffle/pool channel. Cumulative erosion data measured with bank pins after four 2.0 to 2.5-year return period flows from September 1996 to July 1997 were used in the analyses. When integrated as indicated in Rosgen (1996), the BEP indices and NBS estimates were poor predictors of bank erosion. Individually, the grouped BEP ratings and Pfankuch ratings performed relatively well compared to grouped NBS estimates in predicting erosion; however, the variability of erosion was large within each rating group. Linear regression between erosion and BEP numerical indices and Pfankuch scores was significant (a = 0.05), but variability was high (illustrated by low r² values). Regression between erosion and NBS estimates was not significant.     

Primary cell-culture of the digestive gland of the marine mussel Mytilus edulis: a time-course study of antioxidant- and biotransformation-enzyme activity and ultrastructural changes

The extent to which the American lobster, Homarus americanus (H. Milne-Edwards), utilizes estuarine habitats is poorly understood. From 1989 to 1991 we examined lobster movements in and around the Great Bay estuary, New Hampshire using tag/recapture and ultrasonic telemetry. A total of 1212 lobsters were tagged and recaptured at sites ranging from the middle of Great Bay, 23.0 km from the coast, to Isles of Shoals, 11.2 km offshore. Twenty-six lobsters equipped with ultrasonic transmitters were tracked for periods ranging from 2 weeks to >1 year. Most lobsters moved <5 km toward the coast, with those furthest inland moving the greatest distance. Lobsters with transmitters moved in a sporadic fashion, with residency in one area for 2 to 4 weeks alternating with rapid movement to a new location (mean velocity = 0.3 km d⁻¹, 1.8 km d⁻¹ max.). Site of release influenced distance moved, but there was no significant relationship between lobster size and distance traveled, days at large, or rate of movement. Most movement into the estuary occurred in the spring, while during the remainder of the year there was a strong tendency to move downriver, toward the coast. These seasonal migrations of estuarine lobsters may enhance their growth and survival by enabling them to avoid low salinity events in the spring and fall, and to accelerate their growth in warmer estuarine waters during the summer. Received: 26 January 1996 / Accepted: 22 January 1999     

AGRICULTURAL LAND USE IMPACTS ON BACTERIAL WATER QUALITY IN A KARST GROUNDWATER AQUIFER1

ABSTRACT: The impact on water quality by agricultural activity in karst terrain is an important consideration for resource management within the Appalachian Region. Karst areas comprise about 18 percent of the Region's land area. An estimated one-third of the Region's farms, cattle, and agricultural market value are on karst terrain. The purpose of this study was to compare fecal bacteria densities in karst groundwater impacted by two primary agricultural land uses in central Appalachia. Fecal bacteria densities were measured in cave streams draining two primary land management areas. The first area was pasture serving a beef cow-calf operation. The second area was a dairy. Neither area had best management practices in place for controlling animal wastes. Median fecal coliform and fecal streptococcus densities were highest in cave streams draining the dairy. Median fecal coliform densities in the dairy-impacted stream were greater than 4,000 CFU/100 ml and the median fecal coliform densities in the pasture-impacted streams were less than 10 CFU/100 ml. Median fecal streptococcus densities in the same streams were greater than 2,000 CFU/100 ml and 32 CFU/100 nil, respectively. A second dairy, with best management practices for control of animal and milkhouse waste, did not appear to be contributing significant amounts of fecal bacteria to the karst aquifer. It was concluded that agriculture was affecting bacterial densities in the karst aquifer. New management practices specifically designed to protect karst groundwater resources may be one way to protect the groundwater resource.     

The inactive temporary component: an unexplored fraction of meiobenthos

Numerous morphotypes and great abundances of resting stages falling within the meiobenthic size-range were found in meiobenthos samples collected in a coastal lagoon of the North Adriatic Sea. Biodiversity, abundances and energetic values of both active and inactive meiobenthic organisms were analysed by the traditional techniques of meiobenthology. Inactive stages were represented by more than 100 morphotypes and formed 52% of the meiobenthos in terms of numbers of individuals. Inactive meiobenthos came mostly from plankton: the second and third most abundant groups of all meiobenthic organisms were the eggs of a rotifer and the cysts of a dinophyte, respectively. Resting stages of plankters fit the definition of temporary meiobenthos, making up the “inactive temporary meiobenthos”, but they are usually not considered in meiobenthology. The diversity and abundance of the meiobenthos is, thus, currently underestimated; this leads to neglect of the role of meiobenthos in several processes linking different ecosystems. It is hypothesised, for instance, that the meiobenthic resting stages of planktonic organisms (besides being the “seeds” for the perpetuation of planktonic communities) might also be the prey of meiofaunal organisms with piercing mouth parts. If this proves correct, a regulatory role might be proposed for the meiofauna in respect to plankters with benthic stages. Received: 10 September 1998 / Accepted: 12 April 1999     

Movements of tiger sharks (Galeocerdo cuvier) in coastal Hawaiian waters

The giant clam Tridacna crocea harbors in the mantle tissue symbiotic microalgae commonly called zooxanthellae. Isolated zooxanthellae release glycerol into the medium in the presence of mantle tissue homogenate (MH), but it is not clear whether the cells do so in situ. In order to determine the photosynthetic products released by zooxanthellae in the mantle of the giant clam we traced photosynthetic fixation products from ¹³C- and ¹⁴C-bicarbonate both in the clam and in isolated zooxanthellae (IZ) in the presence or absence of MH. After 15 min incubation in the absence of MH the IZ released less than 0.6% of the fixed labeled carbon, mainly as glucose. The major intracellular photosynthates were neutral lipids, which constituted 20 to 40% of the total extractable ¹⁴C. In the presence of MH, the IZ released up to 5.6% of the total fixed ¹⁴C, mostly as glycerol, and the major intracellular photosynthate was glucose. In an intact clam incubated in sea water containing ¹⁴C-bicarbonate, 46 to 80% of the fixed ¹⁴C was translocated from the zooxanthellae to the host tissues. Most of the ¹⁴C in the hemolymph, in the isolated zooxanthellae and in intact mantle tissue (containing zooxanthellae) was recovered as glucose. No ¹⁴C-glycerol was detected in the mantle after 1 to 30 min incubation, and, even after 60 min, far less ¹⁴C-glycerol was synthesized than by IZ in the presence of MH. The possibility that in clam tissue glycerol is converted to glucose was examined by tracing the labeled carbon from ¹⁴C-glycerol injected into the adductor muscle. After 5 min incubation, no labeled glucose was found in the hemolymph, but after 60 min, some 20% was found as glucose. Thin slices containing zooxanthellae, cut from the surface of the mantle, fixed inorganic carbon supplied as NaH¹⁴CO₃ in the medium and mainly released ¹⁴C-glucose. The addition of MH to the surrounding medium did not affect the release rate or form of release product. When the slices were cut into smaller pieces, however, the ratio of glycerol to glucose in the release product increased. These results indicate that in the presence of MH the metabolism of isolated zooxan- thellae was different from that of zooxanthellae in the mantle. In the presence of MH, isolated zooxanthellae release mostly glycerol, whereas in the mantle they release glucose. Received: 18 February 1998 / Accepted: 4 December 1998     

Lethal and sub-lethal effects of phototrophic endoliths attacking the shell of the intertidal mussel Perna perna

Animals that bore into calcareous material can cause considerable damage to molluscan shells. In contrast, smaller microbial phototrophic endoliths have until recently been thought of as relatively benign. Phototrophic endoliths (primarily cyanobacteria) infest the shells of 50 to 80% of midshore populations of the mussel Perna perna (L.) in South Africa. This infestation causes clearly visible shell degradation, and we record here ecologically important lethal and sub-lethal effects (e.g. changes in growth and reproductive output) of the endoliths on their mussel hosts. Endolith infestation reduced the strength of shells significantly and also affected shell growth. In situ marking of shells, using the fluorochrome calcein, showed that infested and non-infested mussels increased in shell length at the same rate. However, the rate of increase in shell thickness (associated with shell repair) was significantly faster in infested than in uninfested individuals. This increase in the rate of shell thickening was not sufficient to compensate for rapid endolith-induced shell degradation and, around the site of adductor muscle attachment, infested shells were thinner than their uninfested counterparts. The shells of 18% of recently dead mussels had holes induced by endolith erosion. This effect was highly size dependent, and the proportion of mortality due to endoliths rose to almost 50% for the largest mussels. The re-routing of energy due to shell repair had important sub-lethal effects on the reproductive rates of mussels. During the reproductive period, mean dried flesh mass for large (>70 mm), non-infested P. perna was substantially higher than for infested individuals. This difference was almost entirely due to differences in gonad mass, which was approximately 100% higher for non-infested mussels. We conclude that, by attacking the shell, phototrophic endoliths reduce both the longevity and reproductive output of large mussels on the midshore. Received: 26 January 1999 / Accepted: 17 August 1999     

Winners and Losers in a World with Global Warming: Noncooperation, Altruism, and Social Welfare

In this paper, global warming is an asymmetric transboundary externality which benefits some countries or regions and harms others. We use a simple two-country model to analyze the effects of global warming on resource allocations, the global-warming stock, and national and global welfare.     

Heavy Metal Toxicity Responses of Two Willow (Salix) Varieties Grown Hydroponically: Development of a Tolerance Screening Test

The E.U. funded BIORENEW project is investigating bioremediation of industrially degraded land using biomass fuel crops, including willow. One of its goals is to develop a rapid screening test to assess the metal tolerance of large numbers of willow varieties. This should reflect how a plant will respond to heavy metals under various field conditions and in the long term. A preliminary experiment tested two varieties of contrasting ability to thrive in metal-contaminated soils. Trees were exposed to a metal cocktail in three different strengths of background solution. An appropriate strength solution (1/4 strength Hoaglands) was identified for differentiating variety performance, based on its effect on the biomass of plant fractions relative to control fractions. This is a response to heavy metals which can be quantified rapidly and simply. The relative performance of the varieties was comparable to their performance in field studies. This test will be used to assess the tolerance of further varieties.     

Contradictory findings in studies of sex ratio variation in roe deer (Capreolus capreolus)

Patterns of sex ratio variation and maternal investment reported in the literature are often inconsistent. This could be due to intra- and inter-specific variation in social systems, but may also be a result of the a posteriori nature of much of this type of analysis or the testing of models which are inappropriate. Two recent papers reported directly opposed results concerning variation in offspring sex ratios in relation to maternal condition in roe deer, interpreting the results as support for the Trivers and Willard model and for the local resource competition hypothesis, respectively. In this paper, we present data on offspring sex ratios and early juvenile body weight from two long-term studies of this species to test predictions arising from these two models concerning sex biases in litter composition and maternal care. First, we observed no consistent pattern of sex differences in an index of weaning weight or body weight at 1 month old in either population, indicating a lack of sex bias in maternal care. However, in one population, higher maternal body weight was associated with higher juvenile body weight of daughters, but not of sons. Secondly, we found a negative, but not statistically significant, relationship between maternal body weight and litter sex ratio such that heavier females tended to produce more daughters and lighter females to produce more sons. These results indicate that roe females which have additional investment potential available do not invest it in sons, as predicted by the Trivers and Willard model. Our results may provide some support that roe deer are subject to local resource competition acting at the level of the individual mother; however, the fact that particular trends in sex ratio data can be explained in functional terms provides no indication that they are actually adaptive. Received: 9 December 1997 / Accepted after revision: 11 November 1998